1. Field of the Invention
The present invention relates to an engine lubrication control system for adjusting the hydraulic pressure that is supplied to respective channels in a lubricating oil feeding device of an engine, or more particularly in a lubricating oil feeding device provided with a cam shaft supply channel for feeding lubricating oil to a cam journal or the like of a cylinder head, and a crank shaft supply channel for feeding lubricating oil to a crank shaft, a connecting rod or the like of a cylinder block.
2. Description of the Related Art
Conventionally, since oil that is needed by sliding parts of the engine such as a crank shaft and a cam shaft or cam shaft mechanical sections is supplied by an oil pump that is driven by the engine, the pressure of the oil that is supplied from the oil pump to the respective components of the engine will change substantially in proportion to the speed of the engine. Thus, depending on the engine speed, there are cases where the discharge pressure becomes greater than necessary, and there is a problem in that the friction of the oil pump increases more than necessary and unneeded work is thereby increased. In view of this, attempts are being made to achieve an appropriate discharge pressure in accordance with the engine speed.
As a lubrication control system for achieving the foregoing object, there is the type disclosed in, for example, Japanese Patent Application Publication No. 2009-264241. Japanese Patent Application Publication No. 2009-264241 is now briefly explained. The reference numerals used in the explanation are cited as is from Japanese Patent Application Publication No. 2009-264241. Foremost, oil is pumped up from an oil pan 10 by an oil pump 12, and fed to a first oil supply route 16a (lower route), and a second oil supply route 16b (upper route).
The first oil supply route 16a is mainly a route for supplying oil to a bearing 18 of the crank shaft, and the second oil supply route 16b is a route for supplying oil, for instance, to a valve gear 20. A hydraulic pressure control valve 22 for controlling the oil content to be supplied to the bearing 18 of the crank shaft is disposed above the first oil supply route 16a. The hydraulic pressure control valve 22 is configured so that its output hydraulic pressure is controlled by the control unit 24.
The control unit 24 is controlled by an engine speed sensor 26, an engine load sensor 28, an oil temperature sensor 30, and a hydraulic pressure sensor 32. Provided is a relief valve 34 which relieves the excessive hydraulic pressure from the oil route between the oil pump 12 and a filter 14 to the oil pan 10 when the hydraulic pressure exceeds a predetermined value. In the foregoing configuration, the hydraulic pressure control valve 22 is electronically controlled by the control unit 24.